<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>变量</title>
</head>
<body>
    <script>
        var num1 = 070; //八进制，等于十进制的56
        var num2 = 0x1f; //十六进制，等于十进制的31
        console.log(num1,num2)
        //js保存的值不会无穷大 当数据超出时会转化成特殊的数据类型 Infinity

        console.log(isFinite(21)); //返回 ture
        console.log(isFinite("hello world")); //返回 false
    </script>
</body>
</html>